Greetings all. My wife's 2004 HCH was showing IMA and check engine lights a few months back, after doing the research it seemed like the battery was dead, so Replaced it with a new battery pack from Bumblebee.

Installed it myself, reset the CEL, all good to go. First 6 weeks no problems, no CELs, MPG was back up in the mid-40s.

Last week, CEL came on while the wife was on an extended trip. She had driven for about 5 hours when the CEL came on. Code reads P2000 Mod 11.

Also on that drive the indicated mpg began dropping, and now shows 26MPG.

I think the P2000 CEL indicates an issue with the oxygen sensors, right? Any connection to the battery pack being replaced? Anyone else seen your mpg drop that sharply with a P2000 code?

Appreciate any help! Hope to have an idea of what is going on before having to go to a repair shop.

 

I believe the P2000 code for an 04 HCH would be the back catalytic converter. Not sure if the battery replacement would effect that?

 

Replacing the battery will not have an impact on your O2 sensors or the catalytic converters.

 

Did a little investigating, and I began to suspect the EGR valve. I took the old one off and it was VERY crudded up. I went ahead and replaced it with a new one, and also cleaned the chambers on the intake.

Meh. Doesn't seem to have fixed the MPG issue. I reset the CEL using my code-reader, and the CEL hasn't come back. But mileage is still in the toilet.

May have to take it in to get a diagnosis. Very frustrating. Just dropped $2500 on a new hybrid battery, and was hoping to see improved mpgs, but seeing the opposite so far.

 

The o2 sensor fault is nothing to do with the ima battery.

Sort the new fault code issues and the mpg will return to normal.

You have just been unlucky with the timing.